<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<script>
		function Foo() {
		    var i = 0;
		    return function() {
		        console.log(i++);
		    }
		}
		 
		var f1 = Foo(),
		    f2 = Foo();
		f1();
		f1();
		f2();
	</script>
</body>
</html>